1. Technical Field
The present invention relates to a screen unit.
2. Related Art
A screen unit is known as a unit provided with a screen which reflects projection light projected from a projection type display apparatus such as a projector to display an image. A certain type of this screen unit known in the related art has a stretching and contracting mechanism which stretches and contracts the screen. The screen unit further has a holding unit which holds one end of the screen, and a winding unit which holds the other end of the screen as a component around which the screen is wound. The winding unit has a spring member which constantly exerts a pulling force on the screen in the winding direction.
Generally, the other end of the screen is fixed to the spring member or other parts within the winding unit via an adhesive double coated member, while the one end of the screen is fixed to the holding unit via a structure for fixation such as an adhesive double coated member or a structure which uses a fixing method such as pinching and insertion into a groove.
According to a screen for a projection type display apparatus disclosed in JP-A-9-34014, which screen is combined with the projector-incorporated projection type display apparatus into one body, a plurality of attachment plates for fixation of the outer periphery of the screen main body are attached to abase frame in such a condition that the attachment angles of the attachment plates with respect to the base frame can be arbitrarily controlled. In this case, the surface of the screen main body can be adjusted to a flat shape by using control screws capable of controlling the attachment angles of the attachment plates.
Generally, the flatness of a screen decreases by processing distortion during manufacture, change with an elapse of the use period, or for other reasons. The decrease in the flatness distorts a display image on the screen produced by the reflection of the light projected from the projector, which may degrade the image quality. Moreover, in case of the screen the parts of which in the area of the winding unit and the holding unit are completely fixed as in the above related art, these fixing positions cannot be easily adjusted after fixation of the screen. Therefore, sufficient positional accuracy is required at the time of fixation of the screen during the manufacture of the screen unit.
Accordingly, such a screen unit which has a structure simple and capable of easily controlling the flatness of the screen has been demanded.